- Balto of the Blue Dawn, by Mary Pope Osborne ; illustrated by Sal Murdocca
- Dinosaurs, a nonfiction companion to Magic tree house #1: Dinosaurs before dark, by Will Osborne and Mary Pope Osborne; illustrated by Sal Murdocca
- The knight at dawn, by Mary Pope Osborne ; illustrated by Sal Murdocca
- The knight at dawn, by Mary Pope Osborne ; illustrated by Sal Murdocca
- Soccer on Sunday, Mary Pope Osborne ; illustrated by Sal Mardocca
- Horse heroes, by Mary Pope Osborne and Natalie Pope Boyce ; illustrated by Sal Murdocca
- Heroes for all times, by Mary Pope Osborne and Natalie Pope Boyce ; illustrated by Sal Murdocca
- Winter of the ice wizard, by Mary Pope Osborne ; illustrated by Sal Murdocca
- Twister on Tuesday, by Mary Pope Osborne ; illustrated by Sal Murdocca
- Ghosts, a nonfiction companion to A good night for ghosts, by Mary Pope Osborne and Natalie Pope Boyce ; illustrated by Sal Murdocca
- Summer of the sea serpent, Mary Pope Osborne ; illustrated by Sal Murdocca
- Twisters and other terrible storms, a nonfiction companion to Twister on Tuesday, by Will Osborne and Mary Pope Osborne ; illustrated by Sal Murdocca
- Knights and castles, by Will Osborne and Mary Pope Osborne ; illustrated by Sal Murdocca
- Tsunamis and other natural disasters, a nonfiction companion to Hide tide in Hawaii, by Mary Pope Osborne and Natalie Pope Boyce ; illustrated by Sal Murdocca
- Magic tricks from the tree house, an activity companion to magic tree house #50: hurry up, Houdini!, Mary Pope Osborne and Natalie Pope Boyce ; illustrated by Sal Murdocca